1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel having a discharge space with a phosphor layer.
2. Description of the Related Art
Plasma display panels are flat display devices in which discharge gas is injected between two or more substrates on which a plurality of discharge electrodes are disposed and vacuum ultraviolet rays generated by discharge of the discharge electrodes excite a phosphor material of a phosphor layer to display desired numbers, letters or images.
The plasma display panels can be classified as alternating current (AC) plasma display panels or direct current (DC) plasma display panels according to the operating principle of the driving voltage applied to discharge cells (e.g., according to their discharge modes). Also, plasma display panels can be classified as surface discharge type or facing discharge type plasma display panels according to the orientation of the discharge electrodes.
FIG. 1 illustrates a conventional three-electrode surface discharge type plasma display panel 100 including a first substrate 101, a second substrate 102 facing the first substrate 101, a sustaining discharge electrode pair 103 including an X electrode 104 and a Y electrode 105 which are formed on an inner surface of the first substrate 101 (or a surface of the first substrate 101 facing the second substrate 102), a first dielectric layer 106 which covers the sustaining discharge electrode pair 103, a protection layer 107 coated on the first dielectric layer 106, an address electrode 108 formed on the second substrate 102 and disposed to cross the sustaining discharge electrode pair 103, a second dielectric layer 109 covering the address electrode 108, barrier ribs 110 installed between the first and second substrate 101 and 102, and red, green, and blue phosphor layers 111 formed in discharge cells. In the space between the combined first and second substrates 101 and 102, discharge gas is injected to form a discharge region.
In the conventional plasma display panel 100, an electric signal is applied to the Y electrode 105 and the address electrode 108 to select discharge cells and then electric signals are alternately applied to the X and Y electrodes 104 and 105 so that surface discharge is generated from a surface of the first substrate 101 and thus ultraviolet rays are generated, and in turn excite the phosphor layers 111 of the selected discharge cells to emit visible light to realize a still image or a moving image.
However, the conventional plasma display panel 100 has the following problems.
First, since not only the sustaining discharge electrode pairs 103, but also the first dielectric layer 106 and the protection layer 107, are formed on the inner surface of the first substrate 101, a transmission ratio of visible light generated in the discharge cells is less than 60%. Thus, the conventional plasma display panel 100 cannot be a highly efficient flat panel device.
Second, when the conventional plasma display panel 100 is operated for a long period of time, discharge is diffused toward the phosphor layer 111, and charge particles of the discharge gas generate ion sputtering in the phosphor layer 111 and this can cause permanent latent images.
Third, since discharge is diffused from discharge gaps between the X electrodes 104 and the Y electrodes 105, namely, along the plane of the first substrate 101, a space usability ratio of all discharge cells is relatively low.
Fourth, when a high density discharge gas containing Xe gas having 10% by volume or higher is injected into the discharge cells, the number of charge particles and excited states are increased by ionization and excitation of elements, thereby increasing brightness and discharge efficiency; however, the initial discharge firing voltage is also disadvantageously increased because of the high density Xe gas.